A Titania Nanotube-Array Room-Temperature Sensor for Selective Detection of Hydrogen at Low Concentrations
Abstract:A tremendous variation in electrical resistance, from the semiconductor to metallic range, has been observed in titania nanotube arrays at room temperature, ≈25 °C, in the presence of ≤1000 ppm hydrogen gas. The nanotube arrays are fabricated by anodizing titanium foil in an aqueous electrolyte solution containing hydrofluoric acid and acetic acid. Subsequently, the arrays are coated with a 10 nm layer of palladium by evaporation. Electrical contacts are made by sputtering a 2 mm diameter platinum disk atop the Pd-coated nanotube array. These sensors exhibit a resistance variation of the order of 104 in the presence of 100 ppm hydrogen at 25 °C. The sensors demonstrate complete reversibility, repeatability, high selectivity, negligible drift and wide dynamic range. The nanoscale geometry of the nanotubes, in particular the points of tube-to-tube contact, is believed to be responsible for the outstanding hydrogen gas sensitivities.
Document Type: Research Article
Publication date: September 1, 2004
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